Question

我有CASE语句，如下所示：

SELECT CASE 
WHEN <expression>> BETWEEN 0 AND 10 THEN '0-10'
WHEN <<expression>> BETWEEN 11 AND 20 THEN '11-20'
WHEN <<expression>> BETWEEN 21 AND 30 THEN '21-30'
...

这很好用，但看起来很难看。

我想将其转换为如下所示的内容：

SELECT CASE <expression>>
WHEN  BETWEEN 0 AND 10 THEN '0-10'
WHEN  BETWEEN 11 AND 20 THEN '11-20'
WHEN  BETWEEN 21 AND 30 THEN '21-30'
...

显然第二个查询看起来更好，因为我不必多次编写那个复杂的表达式。但这是错误的。

Incorrect syntax near the keyword 'between'.

有人可以让我知道我在这里做错了吗？

更新

正如所指出的，我已经在我的问题中更改了查询以使范围独占。

Answer 1

您想要的是不可能的，因为between语句的语法需要一个表达式来测试它作为它的第一个参数：

test_expression [ NOT ] BETWEEN begin_expression AND end_expression

所以你仍然坚持使用第一种语法。

在旁注中，您的范围在使用包含范围之间有点偏差，但是案例表达式按顺序进行评估，因此范围实际上是：

WHEN <<expression>> BETWEEN  0 AND 10 THEN '0-10'
WHEN <<expression>> BETWEEN 11 AND 20 THEN '11-20'
WHEN <<expression>> BETWEEN 21 AND 30 THEN '21-30'

Answer 2

使用子查询，但也可以更清晰地优化案例：

SELECT ...,
  CASE 
    WHEN calc >= 100 THEN 'Over 100'
    ELSE CONCAT(calc * 10, ' - ', calc * 10 + 9)
  END AS range
FROM (SELECT *, FLOOR(<<expression>> / 10) as calc
     FROM tableName) x

FLOOR()函数向下舍入到最接近所提供数字的整数。首先将表达式除以10，然后将地板，然后乘以10，得到表达式范围的开始。例如，如果表达式结果为63.4，63.4 --> 6.34 --> 6 --> 60

如果没有要求顶级＆＃34;超过某些值＆＃34;，您可以完全省略CASE，只需CONCAT(calc * 10, ' - ', calc * 10 + 9)即可处理任何范围内的值。

请注意，您的逻辑中存在错误：范围应为0-9,10-19 ......等。此查询也解决了这个问题。

Answer 3

您可以尝试使用子查询

SELECT CASE 
WHEN ColName BETWEEN 0 AND 10 THEN '0-10'
WHEN ColName BETWEEN 10 AND 20 THEN '10-20'
WHEN ColName BETWEEN 20 AND 30 THEN '20-30'
...

FROM
(
 SELECT <<expression>> as ColName
 FROM tableName
) Z

Answer 4

案例陈述有2个变体，两者都有不同，

1. This is used when condition is dyanmically change and output also want to change
SELECT CASE 
WHEN <<expression>> or condition1 THEN output1
WHEN <<expression>> or condition2 THEN output2
WHEN <<expression>> or condition3 THEN output3
WHEN <<expression>> or condition4 THEN output4
END

2.  This is used when condition is same , only output is different same like swith case in c#.
SELECT CASE <<expression>> 
when result1 then output1
when result2 then output2
when result3 then output3
when result4 then output4
END

对于你的问题。在每个when statement中给出条件。

SELECT CASE 
WHEN  <expression>> BETWEEN 0 AND 10 THEN '0-10'
WHEN  <expression>> BETWEEN 10 AND 20 THEN '10-20'
WHEN  <expression>> BETWEEN 20 AND 30 THEN '20-30'


SELECT CASE 
WHEN 1 = 1 THEN 'YES'  --NEED THE EXPRESSION OF EACH WHEN, IF RESULT IS TRUE, THEN "THEN STATMENT IS OUTPU ELSE NEXT WHEN STATEMENT
WHEN 2 = 2 THEN 'YES'
WHEN 1 = 2 THEN 'NO'
ELSE   --DEFAULT VALUE IF ALLABOVE FAILED
    'NA'
END

Answer 5

使用CTE：

;WITH cte as
(
    SELECT <expression>> AS Expression  FROM TableName
)

SELECT CASE
          WHEN Expression BETWEEN 0 AND 10 THEN '0-10'
          WHEN Expression BETWEEN 10 AND 20 THEN '10-20'
          WHEN Expression BETWEEN 20 AND 30 THEN '20-30'
       END AS C
FROM cte

如果表达总是＆gt; 0和间隔是连续的，那么你甚至可以缩短它：

SELECT CASE
          WHEN Expression <= 10 THEN '0-10'
          WHEN Expression <= 20 THEN '10-20'
          WHEN Expression <= 30 THEN '20-30'
       END AS C
FROM cte

Answer 6

使用CROSS / OUTER APPLY表示

DECLARE @a AS TABLE (
a int ,
b INT
);

INSERT INTO @a VALUES (1,2),(4,5),(4,1),(21,32),(32,21),(43,2);


SELECT CASE 
WHEN expr BETWEEN 0 AND 10 THEN '0-10'
WHEN expr BETWEEN 11 AND 20 THEN '11-20'
WHEN expr BETWEEN 21 AND 30 THEN '21-30'
END

FROM @a 
CROSS APPLY (SELECT  CASE WHEN a > b THEN a ELSE b END expr) b

Answer 7

在您的特定情况下，可以执行以下操作。通常-是-我也缺少此选项。
用tst作为（从（values（100,95），选择选择tst。*，（end_n-start_n）/ 10，
大小写（end_n-start_n）/ 10
当为0时为'bucket_0_10'
当1时为'bucket_10_20'
当2时为'bucket_10_30'
其他'bucket_other'
结束
来自tst

但这是静态的。具有上述技巧的简单查询且没有“大小写”，将使其变得动态

在sql server中编写基于BETWEEN运算符的case语句

7 个答案: